The subject matter herein relates generally to signal transmission electrical cables and shielding efficiency for signal conductors.
Shielded electrical cables are used in high-speed data transmission applications in which electromagnetic interference (EMI) and/or radio frequency interference (RFI) are concerns. Electrical signals routed through shielded cables radiate less EMI/RFI emissions to the external environment than electrical signals routed through non-shielded cables. In addition, the electrical signals being transmitted through the shielded cables are better protected against interference from environmental sources of EMI/RFI than signals through non-shielded cables.
Shielded electrical cables are typically provided with a cable shield formed by a tape wrapped around the conductor assembly. Signal conductors are typically arranged in pairs conveying differential signals. The signal conductors are surrounded by an insulator and the cable shield is wrapped around the insulator. However, where the cable shield overlaps itself, an air void is created. The air void affects the electrical performance of the conductors in the electrical cable by changing the dielectric constant of the material near one of the conductors compared to the other of the conductors within the differential pair, leading to electrical signal timing skew.
A need remains for an electrical cable that improves signal performance.